Cheap BMW i3 Transfer Box

No – the BMW i3 does not have a transfer box at any point in its production run. The i3 is a rear-wheel-drive electric vehicle (or range-extender variant) with a single electric motor driving the rear axle directly through a single-speed reduction gear; there is no four-wheel-drive system and therefore no transfer box was ever fitted. If you are seeing a whining or clunking noise from the drivetrain, what you are most likely looking for is the rear reduction gearbox (sometimes called the single-speed transmission or eDrive gearbox), which is the unit that connects the electric motor to the rear wheels – search for that part instead.

Almost certainly, yes – the BMW i3 has never been offered in a four-wheel-drive configuration, so a transfer box does not exist on this model. The part the garage is most likely referring to is the i3's integrated single-speed reduction gearbox, which sits between the electric motor and the rear axle and can develop faults that mimic traditional transmission problems. It is worth asking the garage to clarify whether they mean the rear eDrive gearbox or possibly the motor itself, as these are the only drivetrain units of that type fitted to the i3.

No – the Range Extender variant adds a small two-cylinder petrol engine solely to generate electricity and charge the battery; it does not drive the wheels and does not introduce a transfer box or any additional mechanical drive components. Both the standard i3 BEV and the i3 Rex share the same rear single-speed electric drive unit and remain rear-wheel drive only. If you are sourcing drivetrain parts for a Rex, the relevant unit is still the rear eDrive reduction gearbox, and you should confirm the exact motor and gearbox specification with the breaker against your registration number.

The BMW i3 ran from 2013 to 2022, with a mid-life update in 2017 that introduced the 120Ah battery alongside the original 60Ah and 94Ah units; a further update arrived in 2019. While the fundamental rear-wheel-drive eDrive architecture carried through the whole production run, power output and motor specifications did change across these updates, which can affect whether the reduction gearbox from one generation is a direct swap for another. You should provide your full registration or engine code to the breaker so they can confirm whether the specific unit from an earlier or later car matches your variant before purchasing.